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Risk Assessment Overview
Ash Grove Cement, Chanute, Kansas	June 2000

INTRODUCTION: The Environmental
Protection Agency (EPA) issued a permit on
August 15, 1996, to the Ash Grove Cement
Company in Chanute, Kansas, to burn
hazardous wastes. The permit allows Ash
Grove to burn those wastes for fuel in two
cement kilns at the Chanute plant. Before
the final permit decision was made, EPA
completed an study of the risks posed by
emissions from the burning of hazardous
wastes at the facility. This study is referred
to as the "Multi-Pathway Risk Assessment."

BACKGROUND: EPA Administrator
Carol Browner announced the Agency's
Waste Minimization and Combustion
Strategy in May 1993. EPA's approach,
which links ongoing waste minimization
policy with combustion issues, focuses on
fostering increased waste reduction and
reducing emissions associated with the
combustion of hazardous wastes. One
priority of this strategy requires the use of a
risk assessment as an added step in the
permitting process for hazardous waste
combustion facilities to further ensure the
protection of public health. EPA completed
the risk assessment in 1995, titled "A Multi-
Pathway Risk Assessment for the Ash Grove
Cement Kilns in Chanute, Kansas."

RISK ASSESSMENT METHODS: EPA's
combustion strategy recommends an
assessment of indirect exposure risks (from
locally-produced foods) as well as direct

risks (such as inhalation) from combustion
emissions. The risk assessment is a
mathematical description, using computer
modeling, of the behavior in the environment
of pollutants emitted during combustion.

That modeling is used to predict the
potential impact on human health. EPA's
guidance for risk assessments at hazardous
waste combustors evaluates emission rates at
maximum allowable levels and uses
hypothetical farmers, fishermen, and
residents who eat mostly foods produced
locally. These foods are produced at sites of
predicted maximum air pathway impacts.

The risk assessment is done assuming that
someone lives where the maximum exposure
is predicted to occur. This location is
referred to as the maximum exposed
individual (MEI). A MEI is not a real person
but represents a person who, based on
lifestyle, would have the maximum exposure
to combustion emissions. The lifestyle may
not actually exist in the surrounding
community. An example of a MEI is a
subsistence farmer who never leaves his farm
during his lifetime; the farm is located at the
point of maximum air concentration; and the
farmer has never eaten anything other than
the beef, milk, and vegetables produced on
his farm. The risk assessment would over
estimate the risks from emissions to that
MEI because an actual farmer would at some
time be away from his farm and/or consume
food produced elsewhere during his lifetime.

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All the risk estimates in the risk assessment
report are intended to be that way.

EPA has set targets so combustion will not
pose an unacceptable risk to human health or
the environment. If the risk assessment
estimates that the risk from emissions are
below the targets, then the combustion of
hazardous wastes is believed to be safe. If
the targets are exceeded, EPA will include
requirements in the permit to reduce
emissions to protect human health and the
environment. If emissions cannot be lowered
enough so that the targets are not exceeded,
EPA will deny the facility's permit.

EPA'S RISK ASSESSMENT: EPA

Region 7 in Kansas City, Kansas, completed
a risk assessment of emissions from burning
hazardous waste in the cement kilns at Ash
Grove's facility in Chanute. The risk
assessment used the guidance titled,
"Guidance for Performing Screening Level
Risk Analysis at Combustion Facilities
Burning Hazardous Wastes, April 15, 1994."
The risk assessment completed by EPA went
beyond the Screening Guidance by including
site specific information on local waterbodies
and adding additional exposure pathways,
such as drinking water, that were not
included in the guidance document. The risk
assessment completed by EPA is sometimes
called a "hybrid" risk assessment because
site-specific data was used in place of some
standard assumptions. This hybrid risk
assessment produces results that are more
realistic and accurate. However, the
conservative nature of the assessment was
preserved by using high-end emission rates
and the MEI approach described earlier.
Site-specific information was used to
eliminate some exposure scenarios that were
not realistic for the Chanute area.
The emissions from the combustion of
hazardous wastes in the two kilns at Ash

Grove were measured in trial burns
conducted in the Spring of 1994. During
these trial burns, the emissions were
measured as the kilns were operated under a
variety of conditions. In some cases,
materials, such as cadmium and lead were
added to the hazardous waste feed to test the
air pollution controls at the maximum
allowable feed rates requested by Ash Grove
for its permit. The operating conditions and
feed rates in the permit are based on those
demonstrated in the trial burns. These
operating conditions and feed rates
correspond to the maximum emissions
allowed from the kilns. Therefore, the risk
assessment predicts the worst case risk
estimates. Emissions during normal
operations of the kilns are lower and will not
cause unacceptable risk to human health or
the environment.

OVERVIEW OF ASH GROVE'S
RISK ASSESSMENT: The first step in
EPA's risk assessment for Ash Grove was to
identify the sources of potential risk. EPA
evaluated the emissions from the two cement
kilns burning hazardous waste as the source
of potential risk.

The second step was to measure the
emissions from the burning of hazardous
waste in the two cement kilns. Emission
rates were determined using facility
operation data (waste throughput and time
of operation), waste composition and trial
burn data. A trial burn was conducted in
order to measure the actual emission rates.
The emission rates during the trial burn are
the worst case emission rates. This ensures
that the risk assessment will not under
estimate the risk from emissions.

The third step was to estimate concentration
of emissions at the exposure points.
Emissions from the smoke stack move

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indirectly through the environment to points
where human exposure can occur. Examples
are: deposition into water that is then
consumed by humans; deposition onto soil
where they are absorbed by plants which are
eaten by cows whose milk and meat are
consumed by humans; and washed into lakes
and streams to be taken up by fish that are
consumed by humans. The risk assessment
included indirect pathways such as
consumption of above-ground vegetables,
below-ground vegetables, beef, milk, fish,
water, and soil, as well as direct pathways
such as dermal (skin) exposure to water
and soil.

The fourth step was to characterize human
exposure patterns. There are many factors
that determine how much exposure you have
to the emissions. These factors include
contact rates (i.e. breathing rate, plant
ingestion rate), body weights, and exposure
times. EPA's assumed that the MEI lives to
70 years of age and that the facility operates
for 30 years, during which the MEI is
exposed for the entire time of operation.
These factors are commonly referred to as
the "exposure setting."

The fifth step is to evaluate the appropriate
exposure patterns. These are commonly
referred to as "exposure scenarios." They are
the behavior patterns for a MEI in the
exposure setting. EPA used the following
exposure scenarios: Resident Child, Resident
Adult, Subsistence Farmer, Recreational
Fisherman, Resident Nursing Infant.

Resident in this case means someone who
lives within the area of maximum exposure.
An example of the behavior pattern
assumptions is the Subsistence Farmer who
is presumed to be an adult who consumes all
of his beef and milk from animals raised on
contaminated foliage (and soil) and eats from
a home vegetable garden. The Recreational

Fisherman is assumed to eat vegetables from
a home garden and eat approximately 1.5
pounds of fish per week. The total exposure
for a scenario is determined by summing the
exposure through all of the individual
pathways that a person might encounter.

The sixth step is to estimate the risk. Both
cancer risk and other potential health impacts
were evaluated. Two standard indexes where
used to measure the potential health risk
posed by a pollutant — the cancer risk and
the hazard quotient. EPA believes that a risk
of cancer greater than one cancer case in a
population of 100,000 (often referred to as
"lxl0"5"risk) and a hazard quotient greater
than 0.25 as unacceptable human health
risks. The cancer risk is the probability an
individual will get cancer from exposure to
emissions. The hazard quotient is an
evaluation of non-cancer causing emissions.
A hazard quotient is a ratio of the estimated
daily intake of a contaminant to its reference
dose. The reference dose is a threshold
concentration quantified for each
contaminant based upon critical toxicological
effects, such as liver damage, kidney
damage, and central nervous system
disorders. For chemicals that can have an
effect on the same target organ, the effects
are added together. If the hazard quotient
exceeds one, adverse health effects are
expected to occur.

RESULTS: In EPA's 1995 risk assessment
for Ash Grove, the only exposure that
greatly exceeded acceptable risk criteria was
the Recreational Fisherman's exposure to
mercury. Again, this predicted exposure
level was based on theoretical modeling only,
and not on actual data documenting the
levels of mercury in fish in the Chanute
vicinity. EPA compared the concentrations
predicted by the risk assessment to actual
mercury concentrations in fish from

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Santa Fe Lake. The actual levels of mercury
in the fish were lower than the modeled
concentrations.

PERMIT APPEAL: EPA issued the permit
to Ash Grove and included annual average
feed rate limits for metals in hazardous
wastes. In addition, environmental
monitoring was required for mercury to
ensure that risks from those emissions are
not present in the Chanute vicinity. The
permit was appealed to EPA's
Environmental Appeals Board (the "Board")
in Washington, D.C. The Board determined
that EPA did not provide sufficient
information in the record that demonstrates
that the permit ensures the protection of
human health and the environment from
mercury emissions.

Since the Board's determination, EPA has

revised its guidance on completing risk
assessments. The revised guidance is titled,
"Human Health Risk Assessment Protocol
for Hazardous Waste Combustion Facilities,
EPA530-D-98-001 A, July 1998." EPA has
also released its report to Congress on
mercury titled, "Mercury Study Report to
Congress," (EPA-452/R-97-003, December
1997).

With the availability of new information from
EPA's report to Congress and the new risk
assessment guidance, EPA decided to re-
evaluate the risk estimates for mercury.
Potential emissions of mercury still exceeded
EPA's hazard quotient target of 0.25. EPA
determined that it could reduce the mercury
feed rate allowed in the permit thereby
reducing the hazard quotient to EPA's
target.

Getting Involved in the Permitting Process

All persons on the facility permit mailing list receive notification by Ash Grove about
requested permit modifications and temporary authorizations. If you would like to know if
you are on the facility mailing list or would like to be added to or deleted from the mailing
list, please contact EPA or KDHE at the numbers listed below.

EPA Region 7's Project Manager is Ken
Herstowski, Air, RCR.A and Toxics
Division, 901 N. 5"' St., Kansas City, Kan-
sas 66101, phone 913-551-763 1,
fax 913-551-7947, or email
herstowski .ken@epa.gov

KDHE's Project Manager is Curtis Lesslie,
Bureau of Waste Management, Permits
Section, Building 740, Forbes Field, To-
peka, Kansas 66620, phone
785-296-6562, or email
clesslie@kdhe. state, ks. us

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